EXPLAINER | The Marcellus Shale, Explained
849 stories

The Marcellus Shale, Explained

Scott Detrow / StateImpact Pennsylvania

Marcellus Shale wells flare in Tioga County. When a test well is drilled and there are no pipelines to carry the gas, the gas is burned.

Marcellus Shale is a sedimentary rock buried thousands of feet beneath the earth’s surface.

It stretches from upstate New York south through Pennsylvania to West Virginia and west to parts of Ohio. Named after a town in upstate New York, the rock itself is millions of years old, formed from mud and organic material.

The natural gas created over millions of years as a byproduct of decomposition is trapped in tiny spaces and fissures within the rock. The Marcellus Shale is just one of many shale formations across the world.

When industry speaks of tapping shale gas, it often refers to it as a “shale play.” The Marcellus is one of the first shale plays to be tapped, after the Barnett Shale formation in Texas.

Click on the image to view StateImpact Pennsylvania’s interactive drilling app” credit=”

But how do you know who’s drilling where? StateImpact’s interactive app answers that question, by tracking every single Marcellus Shale well in Pennsylvania. The app tells you who owns each well, what violations drillers have been cited for, and allows you to read articles we’ve published about drilling near the site’s location.

The interactive map allows users to search for wells by company or location, and includes a separate map devoted to tracking what violations are happening where.

StateImpact Pennsylvania

The Shale Play app tracks drillers’ violations.

Each well has its own specific URL you can link to or share via Twitter and Facebook. If you think there’s more we need to know about the drilling site, there’s a space for you to share comments, stories or pictures.

Our app is based on data from DEP’s website. The department updates production information twice a year, and refreshes violation reports about once a month. Data covering the first six months of 2012 became available in mid-August; the next update will come in February.

Some context on the app’s information: StateImpact Pennsylvania initially only tracked wells that were actively producing gas. In June 2012, we updated the app to display every drilled well. That gives a more accurate portrayal of drilling activity.

Latest stories


In this July 27, 2011 photo, the sun shines over a Range Resources well site in Washington, Pa. In 2018, Range paid the highest impact fee of any driller in Pennsylvania.
Updated: June 27, 2019 | 6:56 pm

Gas impact fee revenue rises to 7-year high, boosted by stripper wells

More than half of 2018 total will be paid to counties and municipalities to offset effects of gas drilling
By Jon Hurdle

This 2010 file photo shows Dominion Resources Cove Point terminal in Maryland. It is has been converted from a gas import facility to an export terminal to ship Marcellus Shale gas to Japan and India.

Huntley & Huntley Energy Exploration's Midas Well pad, the first Marcellus shale gas well in the Pittsburgh suburb of Plum.

DEP investigating gas well for water supply complaint in Pittsburgh suburb

Would be first water supply impacted by drilling in Allegheny County
By Reid Frazier

U.S. Steel's Edgar Thomson Plant is in the eastern Pittsburgh suburbs.

A sign warns drivers of natural gas pipeline construction ahead.

A gas well pad in the Tiadaghton State Forest.

Residents pack a Franklin Park borough council meeting Wednesday night in anticipation of a vote on whether to allow natural gas drilling under a park.

Natural gas wells in Lycoming County, Pennsylvania.

Efficiencies, pipelines help propel Pa. gas production in 2018

More pipelines coming online, coupled with high production, means the industry’s focus is shifting to how it can best use the region’s natural gas.

By Amy Sisk

Natural gas wells in Springville Township, Pa.

Natural gas wells in Lycoming County, Pennsylvania.

New website aims to be clearinghouse for shale research

A new online tool aims to provide a library of up-to-date research on the shale oil and gas drilling boom.

By Marie Cusick
LOAD MORE